Unable to render c4d gradient shader in Arnold

[pleiada]

I can't render the c4d gradient material in Arnold. Does anyone knows the solution or knows how to recreate the similar result in Arnold?

https://drive.google.com/file/d/1wRQ4B0_beW2M1qdhTPsgx0VNxidvNwxH/view?usp=sharing

[peter.horvath6V6K3 · Accepted solution]

Did you try the ramp shader?

[pleiada]

Yes, i did. But when I choose circular type there, it doesnt render correctly.

[peter.horvath6V6K3]

The Cinema 4D gradient is set to '3D - Cylindrical' which is not supported by the ramp shader directly. I think the closest you can get is to set the Projection in the texture tag to Cylindrical and play with the scale and offset. Or use a uv_transform and uv_projection set to cylindrical in the shader network.

[pleiada]

I don't see the Projection or uv_transform and uv_projection in the texture tag. Can you say, where is it exactly?

[peter.horvath6V6K3]

Projection parameter in the Texture Tag:

uv_transform and uv_projection shaders:

[peter.horvath6V6K3]

They are basically doing the same thing, so you either set the Projection in the texture tag or use the uv shaders in the network.

[pleiada]

thank you very much!

[pleiada]

Thank you! That worked!

[maxime.d]

Hey Peter,

How can you render the turbulent gradient in c4dtoa?

Thx a lot

Best

[Anonymous]

Is it possible to link the ramp_rgb beginning and end points to nulls the same way you can with the native C4D Gradient shader when using the "3D" type?

[peter.horvath6V6K3]

There's no easy way to do it, I'm afraid. You can use a noise shader and interpolate the ramp input (e.g. U) controlled by a strength value, like this: gradient_noise.zip

However your shading network becomes quite complicated if you need a little more complex input pattern, like diagonal, radial, box, etc.

[peter.horvath6V6K3]

Here's an example of how to replicate the 3D gradient with the ramp shader: https://answers.arnoldrenderer.com/questions/28884/how-to-set-the-shading-mode-of-ramprgb-to-3d-line...

Then you can drag & drop a Null object to the node editor and use its position as the start or end vector. Note, that you may have to scale the value because Cinema 4D uses cm units while Arnold uses meter by default.

[maxime.d]

Thx Peter,

I think the easiest way is to bake the texture directly from C4d, which is a bit a shame. Do you forecast to implement this gradient with C4dtoa? That could be soooo uselful.

Thx

[peter.horvath6V6K3]

No concrete plans yet, but I agree, it would be cool to have this feature implemented in the ramp shader.

[pdebster]

Hi Peter, thanks for this post.

I followed the link to show how to link Null's vector to control the start and end of a linear 3D ramp, but the thread is a few years old, so the example links are dead. Could I kindly ask for a re-post of the linear gradient example, or even a more detailed explanation of how to connect Null position in the node tree.

thanks in advance, Peter Debay

[peter_horvath]

Please find attached the example with the Null objects.

The math is a bit more complex in the 3D space, we have to project the shading point to the line defined by the start and end vectors, hence the dot products in the shader graph.

[pdebster]

Peter, greatly appreciate the quick reply and taking the time to help me out with this, all the best, Peter